A conventional incandescent lamp filament is made of wolfram or tungsten. Such filament, to maintain its long life, must be energized in an environment that is isolated from oxygen, e.g., in a medium vacuum, for example, from 25 to 1×10−3 torr or from 3 kPa to 100 mPa, or high vacuum, for example, from 1×10−3 to 1×10−9 torr or from 100 mPa to 100 nPa, or in an inert gas environment. Therefore, a conventional incandescent lamp must be sealed well and have a cavity that contains a medium vacuum, a high vacuum, or inert gas, so that the lifetime of the filament, which is within the cavity, can be assured.
In addition, because glass is friendly to the environment, durable, inexpensive, and able to be sealed well, it has been adopted to pack components that contain a medium vacuum, a high vacuum, liquid, or gas. For example, glass has been used in manufacturing incandescent lamps, fluorescent lamps, and vacuum tubes. Although glass has these advantages, the temperature generated by the heat-fusing process is high, and glass is vulnerable to cracking during such processes. Therefore, extensive research for developing successful equipment and processes for handling glass is necessary.
FIG. 1 shows a conventional method of producing an incandescent lamp. A lamp filament 12 and an exhaust pipe 20 are pre-fixed on a glass trumpet tube 16, and the above components are hitched together into a glass lampshell 10 that has its open end downward. Flame-heating nozzles 14 heat a neck 102 of the glass lampshell 10, and produce uprising heated airflows 13. In order to have uniform heating, the glass lampshell 10, exhaust pipe 20, and glass trumpet tube 16 are rotated together synchronously in the same direction, and then the neck 102 of the glass lampshell 10 is heated and fused together with the glass trumpet tube 16 as shown in FIG. 2.
FIG. 2 illustrates a conventional incandescent lamp. Both the fused glass trumpet tube 16 and the neck 102 of the glass lampshell 10 forms a cavity 11 that seals the lamp filament 12 inside, and remaining glass lampshell waste 104 falls off because of gravity as the glass lampshell 10 maintains its open end downward, i.e., having its open end facing toward a direction along the direction of the pull of gravity. In addition, the air can be evacuated from the exhaust pipe 20, or inert gas can be filled into the cavity 11 through the exhaust pipe 20. The exhaust pipe 20 is also made of glass, and therefore can be heated and enclosed to tightly seal the lamp filament 12 into the cavity 11. Furthermore, wire 18 is soldered to a lamp head (not shown in FIG. 2), and the lamp head is fixed on the glass lampshell 10.
A Light-Emitting Diode (LED) is a light-emitting device first proposed by U.S. Pat. No. 4,211,955 (Ray) for use as an emitter of a lamp. Ray's LED lamp has a standard lamp base and could directly replace the conventional incandescent lamp. However, since the LED emitter is inside a standard lampshell, or a transparent or half-transparent lampshell, there is poor heat dissipation or over-heat protection measures, and thus it easily leads to over-heat damage to the LED emitter at a working temperature.
U.S. Pat. No. 4,727,289 (Uchida) described improved protection measures and applied it to high-voltage LEDs, it was still not a good solution to solve the above-mentioned over-heat problem.
FIG. 3 shows a conventional LED lamp. LED emitters 24 are first installed on a supporting component 26, which has a tail inserted into a plastic or rubber plug 28. The plastic or rubber plug 28, the LED emitters 24, and the supporting component 26 are then inserted into a glass lampshell 22, and the neck of the glass lampshell 22 is sealed. Furthermore, wire 30 is soldered to a lamp base 32, and the lamp base 32 is fixed on the glass lampshell 22.
The production of incandescent lamps has matured. There are already a number of automatic production processes and equipment that can be used to produce conventional incandescent lamps, and the production cost is relatively low. However, such methods have never been applied to the production of LED lamps, as using incandescent lamp production methods to produce LED lamps has some significant difficulties. For example, as mentioned above, while producing a conventional incandescent lamp, the open end of the glass lampshell 10 must remain downward, i.e., in the direction of the pull of gravity, so that the glass lampshell waste 104 can fall off automatically because of gravity, as shown in FIG. 2. However, during this heating process, the uprising heated airflows 13 (shown in FIG. 1) raise the air temperature inside the glass lampshell 10 to above 300° C., and this high temperature can last for more than 10 seconds. If this conventional method is applied to LED lamps, the high temperature will damage LED emitters, as the temperature that the LED chips can endure is lower than that of wolfram filaments. In addition, the regular material used to pack LED chips, such as plastics and resin, is also not high-temperature tolerable. For example, the temperature tolerance of regular LED chips is below 250° C., and, if exposed to an environment that is above 220° C. for more than 5 seconds, such LED chips will sustain damage. Therefore, the conventional incandescent lamp production method can not be used to pack LED lamps.
Embodiments consistent with the present invention overcome one or more problems with the above prior art.